Survey and Classification of Large Woody Debris (LWD) in Streams Using Generated Low-Cost Geomatic Products

Damian Ortega-Terol,David Hernández-López,Pablo Rodríguez-Gonzálvez,Miguel Moreno

doi:10.3390/rs61211770

Damian Ortega-Terol, David Hernández-López + Show 2 more

Open Access

https://doi.org/10.3390/rs61211770

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Abstract

Water authorities are required to have a survey of large woody debris (LWD) in river channels and to manage this aspect of the stream habitat, making decisions on removing, positioning or leaving LWD in a natural state. The main objective of this study is to develop a new methodology that assists in decision making for sustainable management of river channels by using generated low-cost, geomatic products to detect LWD. The use of low-cost photogrammetry based on the use of economical, conventional, non-metric digital cameras mounted on low-cost aircrafts, together with the use of the latest computational vision techniques and open-source geomatic tools, provides useful geomatic products. The proposed methodology, compared with conventional photogrammetry or other traditional methods, led to a cost savings of up to 45%. This work presents several contributions for the area of free and open source software related to Geographic Information System (FOSSGIS) applications to LWD management in streams, while developing a QGIS [1] plugin that characterizes the risk from the automatic calculation of geometrical parameters.

Highlights

Trees that grow along a stream often fall into the water course due to flooding, erosion, windfall, disease, beaver activity or natural mortality
With the obtained geomatic product, it is easy to detect the large woody debris (LWD) deposited in the river channel
This study describes a successful methodology that assists in decision making for sustainable management of river channels by generating a low-cost geomatic product to detect the presence and positioning of large woody debris (LWD) as a non-intrusive method

Summary

Introduction

Trees that grow along a stream often fall into the water course due to flooding, erosion, windfall, disease, beaver activity or natural mortality. These materials, often referred to as large woody debris (LWD), can include whole trees with the root mass and limbs attached or portions of trees with or without wads and branches. LWD significantly influences the structure and function of small headwater streams. What it contributes to the geomorphic function depends on where it is located relative to the stream channel and the size relative to the channel [2]. An overview of the different roles that woody debris plays in streams, in terms of pros and cons, can be found in [6,7,8,9]

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